bio  website  

location  Stockholm, Sweden  
age  28  
visits  member for  4 years, 10 months 
seen  18 hours ago  
stats  profile views  7,884 
I am interested in the moduli space of curves and also other things. I am currently on parental leave.
3h

awarded  Revival 
Sep 10 
comment 
When are induction and coinduction of representations of Lie groups isomorphic? When they are compact? Semisimple?
@Sasha You may very well be right, but I don't understand why my argument doesn't cut it. Why do you need the condition on the relative canonical class? 
Sep 10 
answered  When are induction and coinduction of representations of Lie groups isomorphic? When they are compact? Semisimple? 
Sep 5 
comment 
$\ell$adic monodromy theorems (over $\mathbb{C}$)
For Q1 I guess you meant to assume that y is in V. I believe the answer is no in general. I guess you know that it's true if V=Y so you're in the situation of the usual invariant cycle theorem. 
Sep 4 
comment 
Feynman integrals in algebraic geometry
@user125763 I'm flattered, but I don't think I have much useful to say about this circle of ideas. (And the question is in any case closed!) 
Sep 3 
comment 
Feynman integrals in algebraic geometry
You should look at the book "Feynman motives" by Marcolli. 
Aug 31 
comment 
Finite subgroups of mapping class groups
"I vaguely recall hearing that Mod(Σ) has no faithful, finite dimensional linear representations."  Actually, it's a major open problem whether or not mapping class groups are linear. 
Aug 27 
comment 
What are TQFTs that are multiplicative under connected sums? Do bordisms with connected sum as monoidal product exist?
@Turion I think მამუკა ჯიბლაძე has answered your question already, but I think it's worth commenting that connected sum is not a bifunctor. Indeed $M \# N$ depends on the choice of a ball in $M$ and in $N$, so it's only well defined up to a noncanonical isomorphism. 
Aug 25 
comment 
symmetric theta structures and arithmetic subgroups
What's the question? 
Aug 23 
comment 
An algorithm and symbolic manipulation for IFTHENELSE
I was indeed tacitly assuming that every IF should be followed by a boolean expression and a THEN, and conversely, that every THEN should be preceded by a boolean and an IF. 
Aug 23 
answered  An algorithm and symbolic manipulation for IFTHENELSE 
Aug 21 
awarded  Enlightened 
Aug 21 
revised 
Is there a higher Grothendieck ring?
added 165 characters in body 
Aug 21 
awarded  Nice Answer 
Aug 21 
revised 
Is there a higher Grothendieck ring?
added 3933 characters in body 
Aug 21 
answered  Is there a higher Grothendieck ring? 
Aug 18 
comment 
Constructing a space with prescribed cohomology ring
@Fedotov Look again at Theorem 1.2 of the AndersenGrodal paper. There is for instance no topological space with mod 5 cohomology ring $\mathbf F_5[x]$, $\vert x \vert = 6$. Your argument seems to hinge on the following lemma, which is false: if $A$ and $B$ are (graded) $\mathbf F_p$algebras which become isomorphic when tensored with $\overline{\mathbf F}_p$, then $A$ and $B$ are isomorphic already as $\mathbf F_p$algebras. 
Aug 18 
comment 
A group allowing exactly 7 group topologies
@VivekShende If $G$ is infinite, then $G \times G \to G$ is not continuous for the cofinite topology. 
Aug 18 
comment 
Constructing a space with prescribed cohomology ring
@Fedotov Did you look at the paper I mentioned? Your claim contradicts for instance the results of ams.org/mathscinetgetitem?mr=1670237 . I don't see why the isomorphism $S \otimes_{\mathbf F_p} \overline{\mathbf F}_p \cong H^\bullet(X,\mathbf F_p) \otimes_{\mathbf F_p} \overline{\mathbf F}_p$ should be Frobeniusequivariant. 
Aug 16 
comment 
Constructing a space with prescribed cohomology ring
@Fedotov This answer is wrong. It is not true that any $\mathbf F_p$algebra occurs as the mod p cohomology of a space. Look at the introduction to the paper that Matthias Wendt linked to, and the references there. 